Underfeed stoker



April 9, 1929. R. s. RsLEY UNDERFEED S'TOKER Filed Dec. 31, 192,1

m. w m m A TTORNEYS Patented Apr. 9, 1929 UNITED STATES l 1,708,739 PATENT OFFICE.

ROBERT SANFORD RILEY, or woRcEsTER, MASSACHUSETTS, ASSIGNOR To RILEY STOKER eonronATIon, A CORPORATION or MASSACHUSETTS.

UNDERFEED STOKER.

Applcatonled December 31, 1921. Serial No. 525,288.

This invention relates to a furnace stoker of the underfeed typein which fuel is fed into rearwardly and downwardly inclined retorts which discharge ash and refuse from the rear ends thereof.

means for decreasing the airv pressure on the overfeed grate below that nof the side wall pressure when desired, but it has been:

impossible to independently decrease the air pressure on the side walls without at the same time reducing the pressure on the overfeed grate.

Independent regulation of the pressure at these different points renders `possible a much more efficient operation of the furnace, as the air may be closely regulated to the condition of the fire and the depth of the fuel bed at different points in the furnace.

A further object of my invention is to provide additional means for separately controlling the air supply to each overfeed grate section in a multiple retort stoker. This also makes for efficiency of operation as it permits the air pressure to be reduced whenever a thin'place occurs in the fuel bedy on a particular overfeed grate section.

A further object is to provide an air admitting dump plate at the rear of the retort,

pivotally mounted on the bridgewall and extending closely adjacent the rear edge ofY the reciprocating overfeed grate. This dump plate may be madein sect-ions and l provide means by which selected sections of the dump plate may be moved independently of other sections thereof.

With these and other objects in view, my invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of 4my invention isshown in the drawings, in which Fig. 1 is a vertical longitudinal section of my improved stoker, taken substantially along the center line of a retort;

Fig. 2 is a partial plan view thereof; and Fig. 3 is a vertical transverse section taken along the line 3 3 in Fig. 1.

Referring to the drawings, I have shown parts of an underfeed stoker of a well known commercial type, Said Stoker comprising a hopper 10 from which coal is fed to a cylinder 11 connected to a stoker retort by a feed chute or casing 12 extending through the front wall 13 of the furnace. A ram 14: is slidable in the cylinder 11 and is regularly reciprocated by a crankshaft 15 rotated by `suitable driving `mechanism including a worm 1G and worm wheel 17. The worm 1G is continuously rotated by suitable driving connections, not shown.

The fuel retorts have a trough-like or U- shaped section and are shown herein asprovided with air-admitting side walls slidable longitudinally of the retort and receivingmotion from the ram 14 through lost mot-ion driving connections 21. Overfeed grate sections 22 are disposed below and at the rear of the sidewalls 2O and are preferably connected for reciprocation therewith.

An air trunk 23 extends beneath the severalretorts of the furnace and is supplied with air under pressure from a fan 2l or in any other desired manner. Air chambers 25 and 26 are formed under the stokers, each chamber being directly connected to the air trunk 23 by short passages controlled by the dampers 27 and 28.

The `air chamber 25 is connected through l passages 25a to the interior of the side walls 20, through which the air passes to the tuy`ere blocks 29 by which the air is admitted 'to the fuel in the retort. For a more complete vdisclosure of the details of this part of the stoker, reference` is made to my prior Patent, No. 1,090,651, issued March 17, 1914i.

The retort walls are support-ed upon plates 30 extending lengthwise of the retorts and at their lower ends these plates form the sides of air passages to the different over- `feed grate sections 22. `A damper 31 is mounted in each of these air passages to control the flow of air to the correspondiv l overfeed grate section. These damper. are preferably supported on arms 32 looselyfpivoted on brackets or bearings 33 eX- tending into the air chamber 26. The separate dampers 31 may each be provided with an operating link or rod 34e extending to the front of the Stoker and having a plurality of notches 35 adapted to be engaged by a keeper 36 to prevent displacement from a desired adjusted position.

cil

Wvith thisconstruction, it is` possible to regulate the air pues/sure inl either ot the .air chambers or 26 by means et the dempers 27 and 2S and it is also possible to control the-'flow' of' air-through a` particular overeed grate section by adjusting the associated damper 3l. The flow of air may be thus regulated in accordance With the conditions atdiierent points in the fuelr bed. Should a thin place occur the air may be reduced or 'entirely shut olf and should the vfuel bed build upto unusualv thickness the-*air pres sure at that particular point may becorrel spond-ingly increased.. p

At the rear of the furnace. I harve shown an air-admitting dump. plate 40, preferably pinotedupon anrailrl casing` 41 positioned below the back yor bridge Wally 42 and Ipartially supportingthe same. The casing 41 isoon'- `.nected by'a pipe or conduit 43 tothe main air trunk 23r and. is provided withl a damper 44 by which Vthe air pressure on the dump plate .may be controlled. f

The. dump 4plate is. preferably made inl sections corresponding in 4number to the nuinberot retorts and each section is provided4 with a depending aria` or bracket 45 connected by a link 46to a crank pin 47 on .an arm 48 fixed to a crankshaft `49. vThe may be varied to. suit the conditions Ain a particular stoker. 'The dininp plates 40 are preferably provided with air admitting Y openings .53r in their bea-ring portions and `the upper part of eachfdump plate is formed as: a grate having. the usual. air passages between: the elements thereof..`

Having described the `.details ot construction oftliis. torni, of. my improved stoker,v the method of. koperation will be readily apparent. llieA fresh fuel is 'lied into the bottom oit eachv retort at its upper or 'tro-nt end and is gradually worked rearward by the movenient ol the reciprocating side Walls 2O and by the continued action o' the feeding ram 14. I

As thefuelreaches the lower rear portion of the:y retort, its. rearward movement is. continuied by the action of the reciprocating overfeed gratesections 22.. rllhe ash and retuse are deposited upon the ,dump plates 40 and the combustion o-..any Lunconsumed fuel thereinwill bemadecomplete by theair entering through the gratesot thednmp plates.

IVhen. the amount of ash .deposited on any particulzu'V4 section of the dump plates becomes excessive, the plates are lowered by `mea-ns of the hand Wheel 50 and the ash and refuse is deposited in the' ash pit.

Having thusv described my invention, it will. be. evident that changes and modifications can be madetherein by those skilled in theart Within the spirit and scope of my invention as set forth in the claims and I do not Wish tobe otherwise limited tothe de- Y tails herein disclosed but What I claim is ll. Any underleed stoker comprising bottomsand longitudinallymovable side Walls,

forming parallel underieed retorts extend1v ing in the direction of fueltriwel', movable, air admitting overfeed grates, forming extensions of theretort bottoms, tuyeies, surmountingv the movable side Walls, a dump plate in the rear of the overleed grates,Y

means dening an. air trunk, means including a partition wall separating said tuyr-es from the over-feed gratas so that'air may be supplied independently to. each,. and

means for independently regulating the.

lloW of air to the tuyeres. andi to the overfeed grates.`

2. An underfeed stoker comprising bottoms, and longitudinally movable. side Walls,

forming parallel underfeed lretorts extend- Y ing-in the direction ofxfuel travel, air admittingq movable overfeed grates, forming extensions of thel ret-.ort bottoms., tuyeres, surmounting the movable side Walls, anV air admitting dump plate. in the rear of. theovereed grates, means delining an air trunk, means including a partition Wall` separating said tuyr-es from the overt-eed grates-.so that air may be supplied independently to each, and independent meansiforv regulating the flow of air to the tuyei-'es, to

the overl-eed grates, and tothe dump plate..

3. An` underfeed stoker comprising bottoms, and side walls forming -parallelunden `feed retorts extending in the direction1 of fuel travel, air admittingl overfeedfgrates,

torming extensions of the retort bottoms, tuyeres surmonnting the side Walls, a.y dump Vplate in the rear of the `overfeed grates, means forming` an air trunk, means incliiding partition Walls separating said tuyeres from the overleed grate, and means including dampers 'for regulating the admission oi airto said tuyres and to the overiieed gratos independently of ,each other, whereby thel air pressure tothe tuyeres maybe controlled and regulated independently vot the air pressure to the. overfeed grates.

4.. In an under'eed stoker, a plurality of fuelA retorts having aireadmitting side'v Walls,

means for supplying air thereto, amovable over'teed grate section at the rear of each retort, means for supplying air thereto, means to contr-.ol the flow of air to theV retort side Walls,v independent means' to control the flow of air to the over-feed grates, and supplementary means to separately control the flow of air to each overfeed grate section.

5. In an underfced Stoker, a plurality of fuel retorts having air admitting side Walls, means for supplying air thereto, a plurality of overfeed grate sections, one at the rear of each retort, means for supplying air to said grate sections, means to control the flow oi. air to the retort side Walls, and separate means to control the flow of air to each overfeed gratesection, whereby the air pressure in the overfeed grate section at the rear of a selected retort may be made equal to, greater than, or less than the air pressure in said retort side Walls.

6. In an under'feed Stoker, a plurality of fuel retorts having air admitting side Walls, means for supplying air thereto, a plurality of movable overfeed grate sections, onev at the `rear of each retort, means for supplying air to said grate sections, meansto control the flow of air to the retort side Walls, and separate means to control the flow of air to each overfeed grate section, whereby the air pressure in the overfeed grate section at the rear of a selected retort may be made equal to, greater than, or less than the air pressure in said retort side Walls.

In testimony whereof I have hereunto affixed my signature. Y

ROBERT SANFORD RILEY. 

